摘要
在610℃下对SAF2906双相不锈钢分别进行了60、90、120、150和180min的QPQ处理,采用OM、SEM、XRD、显微硬度计以及摩擦磨损试验机研究了各试样的组织与耐磨性。研究发现,QPQ处理后的试样渗层组织由表及里依次为氧化层、化合物层和扩散层。其中,氧化层主要由Fe3O4组成,渗N层(化合物层和扩散层)主要物相为CrN、α-N、Fe2-3N和S相。随着渗N时间延长,化合物层生长速度逐渐减缓,缩松程度逐渐加重;同时,渗层孔隙率随着渗N时间的延长而增加,渗层致密性下降。另外,QPQ处理试样的表面硬度高出基材3倍以上,且随着渗N时间的延长呈先增加后下降的变化规律,经120min处理时,硬度(HV0.2)达到峰值,为1 164。干摩擦磨损试验结果表明,QPQ处理试样的耐磨性能比基材提高了20倍以上,最佳渗N时间为120min。磨损表面形貌观察发现,基材的磨损形式为磨粒犁削,而QPQ处理试样的磨损形式为磨粒的显微切削。
SAF2906 duplex stainless steel was nitrided at 610 ℃for 60,90,120,150 and 180min,respectively,then followed by the same post-oxidation process with heating temperature at 400℃for 30 min.The microstructure and wear resistance of the treated samples were investigated by means of OM（optical microscope）,SEM（scanning electron microscopy）,XRD（X-ray diffraction）,microhardness test and wear resistance test.Microstructure observation indicates that the surface layer of the samples after QPQ treatment is composed of oxide layer,compound layer and diffusion layer from the surface to the center.The oxide layer is composed of Fe3O4.The main phase of the nitrided layer,such as compound layer and diffusion layer,consists of CrN,α-N,Fe2-3N and Sphase.With nitriding time increase,the growth rate of the compound layer is gradually slowed down,and the loose microstructure exhibits more serious.Porosity of the surface layer is increased with the extension of time,and its relative density is declined.The surface hardness of QPQ treated samples is 3times more than the substrate,which is first increased and then decreased with increasing in nitriding temperature,and the optimum hardness is1164HV0.2at 120 min.The dry sliding results show that the wear resistance of QPQ treated samples reaches at least 20 times than that of the substrate,and the desirable wear resistance is presented at 120 min.The worn surface morphology observation reveals that the abrasion form of the substrate belongs to plough cutting,while the abrasion form of QPQ treated samples belongs to micro-cutting.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2014年第9期909-913,共5页
Special Casting & Nonferrous Alloys
基金
福建省高等学校新世纪优秀人才支持计划资助项目(JA10014)
